I once saw a video of a young man explaining the importance of his primary language. He explains how his family has migrated through various countries and finally ends up in the US, where they are not wanted or able to feel at home. This lack of belonging causes him and his family to hold on to thier L1 because as he says it, "We don't have our own country so our language is the only thing we have to ourselves."
L1s are important, and it cannot be denied that they do not have an impact on a person, especially if that is all that they have to hold onto from thier past. So it is disheartening when many places discourage the use of L1s in schools and stress English Only. It is doing the students a disservice because if they then decide to abandon their L1, they could end up regretting it later.
Also, it seems illogical that knowing a foreign language from birth is discouraged and not capitalized on in schools, since many careers are calling for bilingual workers as the job market is becoming more and more international.

I totally get what you're saying. While I discourage teachers from using translations (partially because online translations are unreliable, but also because students need to lose the crutches to absorb English more readily), I always encourage separate reading and exploration in the L1. I ask them to teach me phrases and try to find opportunities for them to use and retain their L1. I have tried to make all of my kids aware that being multilingual is a bonus in life. Any ESL teacher with even a day of multiculturalism training knows that language is the most significant part of one's culture; that losing language is abandoning one's heritage.

All I can say is, if schools are compelling students to lose the L1, it is pretty much just plain old racism and cultural assimilation.